Control system for alternating-current commutator-motors.



R. E. HELLMUNID.

CONTROL SYSTEM FOR ALTERNATING CURRENT COMMUTATOR MOTORS.

APPLICATION FILED MAR. 13. I916.

1 ,266,5 93 Patented May 21,1918.

2 SHEETS-SHEET I.

'NHNESSES:

ATTORNEY R. E. HELLMUND. M FOR ALTEHNATING CURRENT COMMUTATOR MOTORS.

APPLICATION FILED MAR 13. I916. 1,266,593.

CONTROL SYSTE Patented May 21, 1918.

2 SHEETS-SHEET 2.

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WITNESSES: I INVENTOR 072% 6 film/z {Ha/Mafia F BY ATTORNEY UNITED STATES PATENT OFFICE.

RUDOLF E. HELLMUN D, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

CONTROL SYSTEM FOR ALTERNATING-CURRENT COMMUTATOR-MOTORS.

Specification of Letters Patent.

Patented May 21, 1918.

Application filed March 13, 1916. Serial No. 83,778.

To all whom it may concern:

Be it known that I, RUDOLF E.-HELLMUND, a subject of the Emperor of Germany, and a resident of Pittsburgh, in the county .of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Control Systems for Alternating Current Commutator-Motors, of which the following is a specification.

My invention relates to systems of control for alternating-current motors of the compensated, commutator type, and it has for its object to provide a system of the character designated whereby the motor may be started and accelerated in a smooth anduniform manner with ample torque, freedom from sparking, and with other desirable operating characteristics.

In the accompanying drawing, Figure 1 is a diagrammatic view of an alternatingcurrent motor of the compensated commutator type together with its'attendant supply and control circuits embodying a pre- 7 ferred form of my invention; Fig. 2 1s a sequence chart illustrating the order of switch operation in the circuit of Flg. 1 in accelerating the motor thereof in accordance with my invention; Fig. 3 1s a dlagrammatic view of a modification of the system shown in Fig. 1; Fig. 4 is a sequence chart setting forth the order of switch operation in the circuit of Fig. 3, Fig. 5 is a group of simplified diagrammatic views illustrating the development of the connections of the system of Fig. 1 when the switches thereof are operated in accordance with the dlsclosure of Fig. 2; and Fig. 6 is a similar developmentof the system of Figs. 3 and 1.

In the operation of alternating-current, commutator motors of the compensated type, it is customary to connect the cross and main field windings and the armature winding across a source of alternating-current in substantially the order indicated with an intermediate tap from the source to a point between the cross and main field windings, thus producing what is known as the doubly-fed connection. By adjusting the point of connection of said intermediate tap to the source, the voltage 1mpressed' upon the cross field winding may be ad justed with respect to that impressed upon the remaining motor windin s and this feature, in conjunction with tie well-"known transformer action between the armature and cross field wlndlngs, enables an extremely effective and flexible control of the amount and phase of the currents in the different portions of the motor circuit to be obtained.

When operating a doubly-fed motor at low speeds, it is desirable that the cross-field winding be quite highly inductive, whereas, when running at high speeds, it is equally desirable that the intermediate connection be quite highly inductive. In accordance with my invention, I combine an inductive device with a doubly-fed commutator motor, inserting said device in series relation with the cross field winding at low speeds and transferring said inductive device to the intermediate tap at higher speeds.

It is customary to start motors, of the type designated, as repulsion motors and still further useis made of said inductive device by connecting it in series with the repulsion motor circuit, whereby the motor voltage is reduced and a greater number of accelerating steps is obtained. Thus, one and the same inductive device is first employed as a current-limiting means during repulsion operation, is then employed to alter the phase of the cross field current during low-speed, doubly-fed operation and is finally employed to alter the phase of the armature and main field currents during high-speed, doubly-fed operation.

Referring to the accompanying drawing for a more detailed understanding of my invention, I show a motor of the compensated commutator type at 15 in Fig. 1, said motor being provided with an armature 16,

a main field winding 17 and with a crossfield winding 18. Energy for the operation of the motor 15 may be obtained from any suitable source, such, for example, as an auto-transformer 19 connected between the trolley 20 of a railway system and ground at 21. The outer brush of the armature 16 may be connected to the source 19 through a switch 1, and said armature may be short circuited through a resistor 22 by means of a switch 2 for repulsion operation. The main field winding 17 is connected permanently in series with the armature 16 at its upper terminal, and its lower terminal may be connected to the inner terminal of the cross field winding 18 by means of a switch 6 or may be connected to an intermediate point in the source 19 by the simultaneous closure of switches 'l and is permanently connected between a point intermediate the switches 4 and 5 and the inner terminal of the cross-field winding 18. The voltage imposed'upon'the outer te'rminal of said cross-field winding may be adjusted by the manipulation "of "suitable switches 7, 8 and 9 and of a preventive de-V vice 24.

Hav ng thus described the arrangement of a system embodying my invention, the

' the switches 1, 2, at, and "T are closed, as im zted in Fig. :2, establishing the connect-ions shown in Fig. The three motor windingsare conngected in series with each ,other and with the inductive device ,23

across a :relatively small portion of the source,- the volta-ge impressed upon 1 the outer cross field terminal being a minimum and the uarniature '16 being short cincuited through thedevice forrepulsion operation. The switch '6 is nthen closed, short .euiitingathe device-2B asindicated'in'li ig.

The transition "to [doublyeted operation is now performed in the iollo-wingananner:

The switch 3 is first vclosedandthe switch i (3 opened,forming-the circuitshown in Fig.

@5311 doubly-fed tap producing a small 321 nature voltage being established and the device 23 bQl'llg inserted n1 series with the cross-field winding '18 T01 reducing the-curthrough the cswitches r wrent "thereof and, zconsequently, the current of the -,armature "l6. The'arinature short ".01 rcuit andnthe device 2:3 are next elnninated while raising the voltage imposed upon the outercross-field'tap, all asshown in Fl x5 -Conditions are now suitable *for doubly fed operation, with a "relatively low voltage upon :theanmature and a high voltage upon the cross-field 'w1nd1-ngs,'the .current of the latter being restricted in amount,

. howevenby'reason of the transformer *relation to-the armature winding. As a final stepythe mid tap connection tothe source is moved to the left, as' 'shown'in Fig. 5 raising'ithe armature voltage and somewhat reducing the (cross-field voltage and, at the same"tii'ne,the device 23 is insertedin said 'interniediz'rt'e "tap by 'opening the switch at, producing conditions suitable for normal operation, the inductive device 23 producing "such pha'se displacement of the portion of the armature current ithat returns to :the source throughthe intermediate tap will *beneficially affect the torque and conunutatin'g conditions of the motor.

Referrin'gto the torm'of myinveiition sh'ownin Fig. '8, the general arrangement .of the eircuiti's as sh'o\\"'n 'in Fig. 1 'with the exception that'interm'ediate tap voltagesiof low and ;of :high "value "may he obtained 3 and 5, respectively,

An inductive device r while including the device in circuit and a tap voltage of intermediate value may be obtained by closing the switch 10- which-also tion 'cin Fig. at, changingo-ver from repul- $101111) doubly-fed operat on w th a; min mum voltage on the-mid tap and with the device 23 in series -."iththe cross-field winding; The switch 10, 'is then closed and the switch 3v opened, the device 2:3 "acting :as a preventive device during this operation and,

as 'a result, the mid tap voltage with respect to the armature is raised and the device 23 is eliminated from the icrossefield circuit. In the POSLtlOIl 1-18, 'the SWltCh &

'isbpenedrand the switch 6 closed, connect- ;ing :the field windings :17 and =18 directly. v

inseries, and the ni-id tap connection isthen shift-ed irom the switch :10 to the switch 5, using the device -2 8'=as 1a ,preventiveqdevice. iln'thei-final connection shown in Fig.

*5, the switches 1, 5, 6, and 7 areclosed,

the armature and main clield windings ibeg connected in series between the switches and'5, with thecrosS-fie-ld winding con nect'ed -in series between'xthe switches- 5 and 7, the inductive' device28 being-conne lted. in,v

the "mid -tap connection to "the "switch 5, as m the 1)I6VIOUS*GIS6.

Mfihlle 1 have sl iown'inyrinventlon intwo of its preferred forms, it will bero-bvious to thosefiskilled in the antgthat it'is susceptible of 'various minor changesnand modifications without departing from the spirit thereof and I desire, :there t'oreythat'onlysuoh limitations shall berplaced' thereupon as are imposed bywtheiprior artor indicated in the app ended claims.

Ifielaim as my invention:

1. The combination with a source of :al- 'te'rnating' currents, of a dyna-mdelectnic machine of the compensated," co-mmutatorxtype,

*an inductive device, means for initially .con- :necting said "machine to said source for operation as a repulsion motor, with" said inductive device in series relation with the cross=field Winding thereof, means *for' subsequently operating said motor'ras vadoublyfed motor, uwith :said inductive device in series with the .crossi-sfield winding thereof, andmeans for finally inserting saidinduc- "the device in the-intermediate "tap of saiddouble=feed connection.

2. :The ,OOmbIHE LtIOD with a .Source-ofaL lGl'llZltlllg currents, of a fdvnamo electnio ma- ,chine lot-the compensated, commutator-type,

an inductive device, means for connecting said machine to said source for doubly-fed operation, with the cross-field winding thereof across a portion of said source and in series with said inductive device and with the armature and main field windings thereof across another portion of said source, and means for thereafter inserting said inductive device in an intermediate tap between said motor and said source.

3. The combination with a source of a1- tcrnating currents, of a dynamo-electric machine of the compensated, commutator type, an inductive device, means for connecting said machine to said source for doubly-fed operation, with said inductive device in series relation with the cross-field winding of said motor, and means for subsequently connecting said inductive device in the intermediate tap between said motor and said source.

4. The combination with a source of alternating currents, of a dynamo-electric maan inductive device, means for initially connecting said inductive device in series relation with the cross-field winding of said machine, and means for subsequently connecting said inductive device in a lead carrying the difference between the armature and cross-field currents of said machine.

In testimony whereof, I have hereunto subscribed my name this 29th day of Feb., 1916.

RUDOLF E. HELLMUND.

Copiee of thin patent may be obtained for five cent: each, by addressing the Commissioner of Patentl,

Washington, D. 0." 

